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Abstract:

A focal-plane shutter includes: a board including an opening; a leading
blade and a trailing blade; a trailing blade lever; a first lever; a
second lever; a self-holding type solenoid; a leading blade electromagnet
and a trailing blade electromagnet; and a set lever.

Claims:

1. A focal-plane shutter comprising: a board including an opening; a
leading blade and a trailing blade capable of opening and closing the
opening; a trailing blade lever capable of driving the trailing blade; a
first lever connected to the leading blade and capable of driving the
leading blade; a second lever arranged coaxially with the first lever,
and having an engagement portion abutting with the first lever to push
the first lever such that the leading blade opens the opening; a
self-holding type solenoid capable of holding the first lever such that
the leading blade opens the opening in a state where the self-holding
type solenoid is not energized; a leading blade electromagnet and a
trailing blade electromagnet respectively capable of holding the second
lever and the trailing blade lever in a state where the leading blade
electromagnet and the trailing blade electromagnet are energized; and a
set lever setting the second lever and the trailing blade lever such that
the second lever and the trailing blade lever respectively abut with the
leading blade electromagnet and the trailing blade electromagnet, wherein
a first mode, where the second lever and the trailing blade lever are set
in a state where the leading blade and the trailing blade open the
opening, or a second mode, where the second lever and the trailing blade
lever are set in a state where the leading blade closes the opening and
the trailing blade opens the opening, is selectively switched.

2. The focal-plane shutter of claim 1, wherein in the first mode, the
second lever is set in a state where the first lever is held by the
self-holding type solenoid, and in the second mode, the second lever is
set in a state where the first lever recedes from the self-holding type
solenoid.

3. The focal-plane shutter of claim 1, wherein the first lever is biased
by a first biasing member such that leading blade closes the opening, and
the second lever is biased by a second biasing member such that the
second lever push the first lever and that the leading blade opens the
opening.

4. The focal-plane shutter of claim 3, wherein in the first mode, the
second lever is set, the first lever is moved by the biasing force of the
first biasing member to cause the leading blade to close the opening in a
state where the second lever is held by the leading blade electromagnet,
and then energization of the leading blade electromagnet is cut off to
cause the first lever to move in accordance with the biasing force of the
second biasing member against the biasing force of the first biasing
member, so that the leading blade opens the opening, and in the second
mode, the second lever is set, and then energization of the leading blade
electromagnet is cut off to cause the first lever to move in accordance
with the biasing force of the second biasing member against the biasing
force of the first biasing member, so that the leading blade opens the
opening.

5. The focal-plane shutter of claim 4, wherein energization of the
leading blade electromagnet is cut off in a state where the second lever
is adsorbed with and held by the leading blade electromagnet, and then
the second lever is rotated by the biasing force of the second biasing
member, so that the first lever abuts with the non-energized self-holding
type solenoid.

6. The focal-plane shutter of claim 3, wherein in the first mode, the
trailing blade lever is set, and then energization of the trailing blade
electromagnet is cut off in a state where the leading blade opens the
opening, so that the trailing blade closes the opening.

Description:

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is a continuation of and claims priority to
International Patent Application No. PCT/JP2011/062654 filed on Jun. 2,
2011, which claims priority to Japanese Patent Application No.
2010-206013 filed on Sep. 14, 2010, subject matter of these patent
documents is incorporated by reference herein in its entirety.

[0005] Japanese Unexamined Patent Application Publication No. 2004-317589
discloses a focal-plane shutter providing with a leading blade
electromagnet, a trailing blade electromagnet, and an actuator capable of
holding a lever opening and closing a leading blade in an non-energized
state.

[0006] The actuator disclosed in Japanese Unexamined Patent Application
Publication No. 2004-317589 includes a stator, a coil, and a rotor. Thus,
the provision of such an actuator might increase a size of the
focal-plane shutter itself.

SUMMARY

[0007] It is therefore an object of the present invention to provide
focal-plane shutters and optical equipment suppressing an increase in
size thereof.

[0008] According to an aspect of the present invention, there is provided
a focal-plane shutter including: a board including an opening; a leading
blade and a trailing blade capable of opening and closing the opening; a
trailing blade lever capable of driving the trailing blade; a first lever
connected to the leading blade and capable of driving the leading blade;
a second lever arranged coaxially with the first lever, and having an
engagement portion abutting with the first lever to push the first lever
such that the leading blade opens the opening; a self-holding type
solenoid capable of holding the first lever such that the leading blade
opens the opening in a state where the self-holding type solenoid is not
energized; a leading blade electromagnet and a trailing blade
electromagnet respectively capable of holding the second lever and the
trailing blade lever in a state where the leading blade electromagnet and
the trailing blade electromagnet are energized; and a set lever setting
the second lever and the trailing blade lever such that the second lever
and the trailing blade lever respectively abut with the leading blade
electromagnet and the trailing blade electromagnet, wherein a first mode,
where the second lever and the trailing blade lever are set in a state
where the leading blade and the trailing blade open the opening, or a
second mode, where the second lever and the trailing blade lever are set
in a state where the leading blade closes the opening and the trailing
blade opens the opening, is selectively switched.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1 is a front view of a focal-plane shutter according to a
present embodiment;

[0010] FIG. 2 is an enlarged view around a first lever and a second lever
illustrated in FIG. 1;

[0011]FIG. 3 is an exploded perspective view of a configuration around
the first lever and the second lever;

[0012]FIG. 4 is an exploded perspective view of the configuration around
the first lever and the second lever;

[0013]FIG. 5 is a side view of the configuration around the first lever
and the second lever;

[0014]FIG. 6 is a timing chart of a focal-plane shutter in a first mode;

[0015]FIG. 7 is an explanatory view of the operation of the focal-plane
shutter in the first mode;

[0016]FIG. 8 is an explanatory view of the operation of the focal-plane
shutter in the first mode;

[0017] FIG. 9 is an enlarged view around the first lever and the second
lever illustrated in FIG. 8;

[0018]FIG. 10 is an explanatory view of the operation of the focal-plane
shutter in the first mode;

[0019] FIG. 11 is an enlarged view around the first lever and the second
lever illustrated in FIG. 10;

[0020] FIG. 12 is an explanatory view of the operation of the focal-plane
shutter in the first mode;

[0021] FIG. 13 is an explanatory view of the operation of the focal-plane
shutter in the first mode;

[0022] FIG. 14 is a timing chart of the focal-plane shutter in a second
mode;

[0023] FIG. 15 is an explanatory view of the operation of the focal-plane
shutter in the second mode;

[0024]FIG. 16 is an explanatory view of the operation of the focal-plane
shutter in the second mode;

[0025]FIG. 17 is an explanatory view of the operation of the focal-plane
shutter in the second mode; and

[0026]FIG. 18 is an explanatory view of the operation of the focal-plane
shutter in the second mode.

DETAILED DESCRIPTION

[0027] A present embodiment according to the present invention will be
described below with reference to drawings.

[0028] FIG. 1 is a front view of a focal-plane shutter according to the
present embodiment. As illustrated in FIG. 1, a focal-plane shutter 1
includes: a board 10; a leading blade 20a; a trailing blade 20b; arms 31a
and 31b; a first lever 40; a second lever 50; a trailing blade drive
lever 60; a leading blade electromagnet (hereinafter referred to as
electromagnet) 70a; a trailing blade electromagnet (hereinafter referred
to as electromagnet) 70b; a self-holding type solenoid (hereinafter
referred to as solenoid) 80; and a set lever 90. The board 10 is made of
a synthetic resin. The board 10 includes an opening 11 having a
substantially rectangular shape.

[0029] The leading blade 20a includes four blades, but a single blade 21a
is illustrated in drawings. Likewise, the trailing blade 20b includes
four blades, but a single blade 21b is illustrated in the drawings.
Additionally, each of the leading blade 20a and the trailing blade 20b
may include five, three, or two blades. FIG. 1 illustrates the leading
blade 20a in an overlapped state and the trailing blade 20b in an
expanded state. In FIG. 1, the leading blade 20a recedes from the opening
11 to open the opening 11, and the trailing blade 20b closes the opening
11.

[0030] As illustrated in FIG. 1, the leading blade 20a is coupled to two
arms, but a single arm 31a is illustrated in the drawings. Likewise, the
trailing blade 20b is coupled to two arms, but a single arm 31b is
illustrated in the drawings. These arms 31a and 31b are each swingably
supported by the board 10.

[0031] As illustrated in FIG. 1, the first lever 40 for driving the arm
31a, the second lever 50, and the trailing blade drive lever 60 for
driving the arm 31b are provided on the board 10. The first lever 40 and
the second lever 50 will be described later. The trailing blade drive
lever 60 includes a pipe portion 65. The pipe portion 65 rotatably fits
onto a spindle portion 15b formed on the board 10. Thus, the trailing
blade drive lever 60 is swingably supported by the board 10 in a
predetermined range. The trailing blade drive lever 60 is provided with a
drive pin 63. The board 10 is provided with an escape slot 13b for
allowing the movement of the drive pin 63. The escape slot 13b has an arc
shape. The drive pin 63 fits into a fitting hole of the arm 31b. Swinging
of the trailing blade drive lever 60 causes the arm 31b to swing, whereby
the trailing blade 20b moves.

[0032] The trailing blade drive lever 60 holds a movable iron piece 67.
The trailing blade drive lever 60 can swing between a position where the
movable iron piece 67 abuts with the electromagnet 70b and a position
where the movable iron piece 67 recedes from the electromagnet 70b. A
biasing spring, not illustrated, fits around the pipe portion 65. The
biasing spring biases the trailing blade drive lever 60 in such a
direction that the movable iron piece 67 moves away from the
electromagnet 70b. That is, the biasing spring biases the trailing blade
drive lever 60 such that the trailing blade 20b closes the opening 11.

[0033] The electromagnet 70b can adsorb the movable iron piece 67, when
energized. The electromagnet 70b includes: an iron core 71b; and a coil
wound around the iron core 71b to energize the iron core 71b. In the
drawing, only the iron core 71b is illustrated. The energization of the
coil generates a magnetic attractive force in the iron core 71b, and then
the iron core 71b can adsorb the movable iron piece 67. In the state
where the movable iron piece 67 abuts with the iron core 71b, the
trailing blade 20b opens the opening 11.

[0034] Next, the first lever 40 and the second lever 50 will be described.
FIG. 2 is an enlarged view around the first lever 40 and the second lever
50 illustrated in FIG. 1. FIGS. 3 and 4 are exploded perspective views of
a configuration around the first lever 40 and the second lever 50. FIG. 5
is a side view of the configuration around the first lever 40 and the
second lever 50. Additionally, in FIGS. 2 to 4, the first lever 40 is
hatched.

[0035] The first lever 40 includes a drive pin 43 fitted into the arm 31a.
The board 10 is formed with an escape slot 13a, having an arc shape, for
allowing the drive pin 43. The first lever 40 is formed with a hole 45
through which a spindle portion 15a provided in the board 10 penetrates.
Therefore, the first lever 40 rotatably fits onto the spindle portion
15a. The first lever 40 holds a movable iron piece 47.

[0036] The spring S1 has a coil shape. One end S11 of the spring S1
engages with an engagement portion 18 formed on the board 10. The other
end S12 of the spring S1 is bent to engage with the first lever 40, as
illustrated in FIGS. 2 and 5. The spring S1 biases the first lever 40
counterclockwise. In other words, the spring S1 biases the first lever 40
such that the leading blade 20a closes the opening 11. The spring S1
corresponds to a first biasing member. The first lever 40 includes an
engagement portion 48 protruding radially outward.

[0037] The second lever 50 is arranged coaxially with the first lever 40.
Specifically, the second lever 50 rotatably fits onto the common spindle
portion 15a onto which the first lever 40 rotatably fits. The second
lever 50 includes a pipe portion 55 which rotatably fits onto the spindle
portion 15a. The spindle portion 15a fitted into the hole 45 of the first
lever 40 and the pipe portion 55 of the second lever 50, so that the
first lever 40 and the second lever 50 are arranged coaxially with each
other. The second lever 50 holds a movable iron piece 57. The spring S2
is arranged around the pipe portion 55. The spring S2 has a coil shape. A
wire diameter of the spring S2 is larger than that of the spring S1, and
the full length of the spring S2 is longer than that of the spring S1. An
elastic restoring force of the spring S2 is greater than that of the
spring S1, under conditions where each deformation amount thereof is the
same.

[0038] One end S21 of the spring S2 engages with a ratchet wheel 100a
illustrated in FIG. 5. The ratchet wheel 100a rotatably fits onto the
spindle portion 15a. The ratchet wheel 100a is formed at its outer
circumference with plural tooth portions. Further, a holding plate 110 is
provided with an engaging pawl which can engage with the tooth portion.
The engagement of the engaging pawl with the tooth portion of the ratchet
wheel 100a prevents the ratchet wheel 100a from being rotated by the
biasing force of the spring S2. That is, the engaging pawl secures the
ratchet wheel 100a. The other end S22 engages with the second lever 50 as
illustrated in FIG. 2. The spring S2 biases the second lever 50
clockwise. The adjustment of the rotational amount of the ratchet wheel
100a adjusts the biasing force of the spring S2. The spring S2
corresponds to a second biasing member.

[0039] The second lever 50 is formed with an engagement portion 58 which
can abut with the engagement portion 48 of the first lever 40. When the
second lever 50 rotates clockwise with the engagement portion 48 and the
engagement portion 58 abutting with each other, the first lever 40
rotates clockwise together with the second lever 50. Also, as for the
first lever 40 and the second lever 50, the second lever 50 rotate
counterclockwise with respect to the first lever 40 such that the
engagement portion 48 and the engagement portion 58 move away from each
other.

[0040] The electromagnet 70a has substantially the same configuration as
the electromagnet 70b, and includes: an iron core 71a; and a coil wound
around the iron core 71a to energize the iron core 71a. In drawings, the
illustration of the coil is omitted. The iron core 71a has a
substantially lateral U-shape. When the coil wound around the iron core
71a is energized, the iron core 71a can adsorb the movable iron piece 57
of the second lever 50.

[0041] The solenoid 80 can adsorb the movable iron piece 47 of the first
lever 40, when not energized. The solenoid 80 includes: a yoke 81 having
a substantially lateral U-shape when viewed from its side; a permanent
magnet 85 assembled into the yoke 81; and a coil, not illustrated, wound
around the yoke 81. Since the yoke 81 is assembled with the permanent
magnet 85, the yoke 81 has given polarities by the influence of the
permanent magnet 85. Thus, the solenoid 80 can adsorb the movable iron
piece 47 of the first lever 40, when not energized. Also, when the coil
wound around the yoke 81 of the solenoid 80 is energized and then the
yoke 81 is excited so as to cancel the polarities generated by the
influence of the permanent magnet 85, the magnetic attractive force
between the yoke 81 and the movable iron piece 47 decreases. Thus, when
the coil of the solenoid 80 is energized with the movable iron piece 47
of the first lever 40 abutting with the yoke 81, the attractive magnetic
force exerted between the yoke 81 and the movable iron piece 47 is
smaller than the biasing force of the spring S1, so that the first lever
40 is rotated counterclockwise by the biasing force of the spring S1 and
recedes from the solenoid 80.

[0042] Next, the set lever 90 will be described. The set lever 90 is
provided for setting the second lever 50 and the trailing blade drive
lever 60 such that the second lever 50 and the trailing blade drive lever
60 respectively abut with the electromagnets 70a and 70b. The set lever
90 is rotatably supported by the board 10. The set lever 90 includes a
pushed portion 93 pushed by a charge member provided in the camera side.
The set lever 90 includes pushing portions 94 and 96. The pushed portion
93, and the pushing portions 94 and 96 protrude outward from the
rotational center of the set lever 90. As illustrated in FIG. 1, the
second lever 50 and the trailing blade drive lever 60 include rollers 54
and 64, respectively.

[0043] The pushed portion 93 is pushed by the charge member of the camera
side, so that the set lever 90 rotates clockwise. In response to this,
the pushing portions 94 and 96 respectively abut with the rollers 54 and
64 to move the second lever 50 and the trailing blade drive lever 60
counterclockwise. This allows the second lever 50 and the trailing blade
drive lever 60 to abut with the electromagnets 70a and 70b, respectively.
Additionally, the set lever 90 is attached with a return spring (not
illustrated) for returning the set lever 90 to an initial position. The
return spring biases the set lever 90 counterclockwise. The set lever 90
illustrated in FIG. 1 is positioned at the initial position. The board 10
is provided with a positioning portion for positioning the set lever 90,
which is biased counterclockwise by the return spring, at the initial
position.

[0044] Next, the operation of the focal-plane shutter 1 will be described.
The focal-plane shutter 1 can selectively switch between first and second
modes. In the first mode, the second lever 50 and the trailing blade
drive lever 60 are set in a state where the leading blade 20a and the
trailing blade 20b open the opening 11. In the second mode, the second
lever 50 and the trailing blade drive lever 60 are set in a state where
the leading blade 20a closes the opening 11 and the trailing blade 20b
opens the opening 11. Firstly, the operation of the focal-plane shutter 1
in the first mode will be described.

[0045] The first mode will be described with reference to FIGS. 1, and 6
to 13. FIG. 6 is a timing chart of the focal-plane shutter 1 in the first
mode. FIG. 1 illustrates an initial state. In the initial state, the
movable iron piece 47 of the first lever 40 is held by the solenoid 80,
the leading blade 20a recedes from the opening 11 to open the opening 11,
and the trailing blade 20b closes the opening 11. When the set lever 90
is rotated clockwise from the initial state, the pushing portions 94 and
96 of the set lever 90 respectively abut with the roller 54 of the second
lever 50 and the roller 64 of the trailing blade drive lever 60 to rotate
the second lever 50 and the trailing blade drive lever 60
counterclockwise, as illustrated in FIG. 7. As illustrated in FIG. 8, the
set lever 90 rotates the second lever 50 and the trailing blade drive
lever 60 counterclockwise until the movable iron piece 57 of the second
lever 50 abuts with the electromagnet 70a and the movable iron piece 67
of the trailing blade drive lever 60 abuts with the electromagnet 70b.

[0046] At this time, the second lever 50 is rotated counterclockwise with
the solenoid 80 adsorbing and holding the movable iron piece 47 of the
first lever 40. Therefore, as illustrated in FIG. 8, the trailing blade
20b recedes from the opening 11 to open the opening 11, while the leading
blade 20a is opening the opening 11. In such a manner, the setting of the
second lever 50 and the trailing blade drive lever 60 is finished. FIG. 9
is an enlarged view around the first lever 40 and the second lever 50 in
the set state of the first mode. In such a way, the movable iron piece 57
abuts with the electromagnet 70a, whereas the movable iron piece 47 abuts
with the solenoid 80. The states illustrated in FIGS. 1, and 7 to 9
correspond to a first state of the timing chart illustrated in FIG. 6.

[0047] In this state, a release button of the camera is pushed, so that
the coil of the solenoid 80 is energized. Therefore, the magnetic
attractive force exerted between the yoke 81 and the movable iron piece
47 is smaller than the biasing force of the spring S1, so that the first
lever 40 is rotated counterclockwise by the biasing force of the spring
S1 as illustrated in FIG. 10. Thus, the leading blade 20a closes the
opening 11. FIG. 11 is an enlarged view around the first lever 40 and the
second lever 50 illustrated in FIG. 10. As illustrated in FIG. 11, the
engagement portions 48 and 58 abut with each other. The state illustrated
in FIGS. 10 and 11 corresponds to a second state of the timing chart
illustrated in FIG. 6.

[0048] Next, the electromagnets 70a and 70b are energized. Therefore, the
movable iron pieces 57 and 67 can be respectively adsorbed with the
electromagnets 70a and 70b, and then the second lever 50 and the trailing
blade drive lever 60 are maintained in the state illustrated in FIG. 10.
Next, as illustrated in FIG. 12, the charge member of the camera side
pushing the set lever 90 recedes from the set lever 90, and then the set
lever 90 is rotated counterclockwise by the biasing force of the return
spring and returns to the initial position. Therefore, the pushing
portions 94 and 96 recede from the rollers 54 and 64, respectively. The
state illustrated in FIG. 12 corresponds to a third state of the timing
chart illustrated in FIG. 6.

[0049] Next, the energization of the electromagnet 70a is cut off, so that
the first lever 40 and the second lever 50 rotate clockwise together. The
leading blade 20a recedes from the opening 11 to open the opening 11. The
first lever 40 and the second lever 50 are rotated clockwise by the
biasing force of the spring S2. In addition, the spring S2 exerts a force
on only the second lever 50. However, since the engagement portion 48 of
the first lever 40 and the engagement portion 58 of the second lever 50
engage with each other as illustrated in FIG. 11, the second lever 50
rotates clockwise, and then the engagement portion 58 rotates clockwise
and pushes the engagement portion 48 clockwise. Therefore, the first
lever 40 rotates clockwise together with the second lever 50. FIG. 13
illustrates an exposing state. The state illustrated in FIG. 13
corresponds to a fourth state of the timing chart illustrated in FIG. 6.

[0050] Additionally, at this time, the movable iron piece 47 of the first
lever 40 abuts with the yoke 81 of the solenoid 80. When the solenoid 80
is not energized, the magnetic attractive force is exerted between the
yoke 81 of the solenoid 80 and the movable iron piece 47. Therefore, the
first lever 40 is suppressed from bounding when the movable iron piece 47
abuts with the yoke 81. This can prevent the leading blade 20a from
partially closing the opening 11 caused by the bounding of the first
lever 40. It is therefore possible to suppress the influence on the image
quality by the bounding of the first lever 40.

[0051] Next, the energization of the electromagnet 70b is cut off, the
trailing blade drive lever 60 is rotated clockwise by the spring not
illustrated, and then the trailing blade 20b closes the opening 11.
Therefore, the state of the focal-plane shutter 1 returns to the initial
state illustrated in FIG. 1. In such a way, the exposure operation is
performed in the first mode.

[0052] As described above, in the first mode, the second lever 50 and the
trailing blade drive lever 60 are set in the state where the opening 11
is opened. Thus, for example, in a case of taking a photograph in a live
view mode of displaying outputs from the image pickup element on a liquid
crystal monitor or the like in real time, the first mode is suitable.

[0053] Next, the second mode will be described with reference to FIGS. 1,
and 14 to 18. FIG. 14 is a timing chart of the focal-plane shutter 1 in
the second mode. From the initial state illustrated in FIG. 1, the coil
wound around the yoke 81 of the solenoid 80 is energized to cancel the
polarities generated in the yoke 81 by the permanent magnet 85. This
decreases the magnetic attractive force exerted between the yoke 81 of
the solenoid 80 and the movable iron piece 47 of the first lever 40. In
this state, the set lever 90 is rotated clockwise by the charge member of
the camera side, so that the pushing portions 94 and 96 of the set lever
90 respectively abut with the rollers 54 and 64 to rotate the second
lever 50 and the trailing blade drive lever 60 counterclockwise, as
illustrated in FIG. 15. At this time, the magnetic attractive force
exerted between the yoke 81 and the movable iron piece 47 is decreased,
so that the first lever 40 is rotated counterclockwise together with the
second lever 50 by the biasing force of the spring S1.

[0054] Therefore, as illustrated in FIG. 16, the movable iron pieces 57
and 67 respectively abut with the iron cores 71a and 71b. Since the first
lever 40 rotates counterclockwise in conjunction with the second lever
50, the leading blade 20a closes the opening 11, and the trailing blade
20b opens the opening 11. In such a way, in the state where the leading
blade 20a closes the opening 11 and the trailing blade 20b opens the
opening 11, the second lever 50 and the trailing blade drive lever 60 are
set. The states illustrated in FIGS. 1, 15, and 16 correspond to a first
state of the timing chart illustrated in FIG. 14. Additionally, FIG. 16
is the same as FIG. 10.

[0055] Next, when a predetermined period elapses from the time when the
release button is pushed, the electromagnets 70a and 70b are energized,
and then the movable iron pieces 57 and 67 are respectively adsorbed with
the iron cores 71a and 71b (the state corresponding to the second state
of the timing chart illustrated in FIG. 14). Next, as illustrated in FIG.
17, the charge member of the camera side recedes from the set lever 90,
and the set lever 90 is rotated counterclockwise by the biasing force of
the return spring not illustrated and returns to the initial position.
The state illustrated in FIG. 17 corresponds to a third state of the
timing chart illustrated in FIG. 14. Additionally, FIG. 17 is the same as
FIG. 12.

[0056] Next, the energization of the electromagnet 70a is cut to reduce
the magnetic attractive force exerted between the iron core 71a and the
movable iron piece 57, so that the second lever 50 is rotated clockwise
by the biasing force of the spring S2 as illustrated in FIG. 18.
Additionally, at this time, the first lever 40 also rotates clockwise in
conjunction with the second lever 50. Therefore, the leading blade 20a
recedes from the opening 11 to open the opening 11. The state illustrated
in FIG. 18 corresponds to a fourth state of the timing chart illustrated
in FIG. 14. Additionally, FIG. 18 is the same as FIG. 13.

[0057] Next, the energization of the electromagnet 70b is cut off, so that
the trailing blade drive lever 60 rotates clockwise, and then the
trailing blade 20b closes the opening 11. The state of the focal-plane
shutter 1 returns to the initial state illustrated in FIG. 1. The
exposure operation is performed in the second mode in such a way.

[0058] As described above, in the second mode, the second lever 50 and the
trailing blade drive lever 60 are set in the state where the opening 11
is closed. Thus, for example, in case of continuous shooting, it is
little necessary to display outputs from the image pickup element on a
liquid crystal monitor or the like at every shooting. Thus, the second
mode is suitable for continuous shooting.

[0059] Also, in the first mode, as illustrated in FIG. 6, the leading
blade 20a starts moving in the set state where the opening 11 is opened,
so that the opening 11 is closed. After that, the leading blade 20a
recedes from the opening 11 to open the opening 11. Next, the trailing
blade 20b closes the opening 11. In this manner, a photograph is taken.
However, in the second mode, as illustrated in FIG. 6, the leading blade
20a starts receding from the opening 11 in the set state where the
leading blade 20a closes the opening 11, so that the opening 11 is
opened. Next, the trailing blade 20b closes the opening 11. In this
manner, a photograph is taken. Thus, in the first mode, the leading blade
20a has to close the opening 11 after the set is accomplished, as
compared with the second mode. For this reason, in case of continuous
shooting, the number of the photographs that can be taken for a
predetermined period in the second mode is larger than that in the first
mode.

[0060] As mentioned above, in the focal-plane shutter 1 according to the
present embodiment, the first mode and the second mode can be selectively
switched by controlling the energization of the solenoid 80. It is
therefore possible to select a mode suitable for a manner of shooting by
use of the single focal-plane shutter.

[0061] Additionally, the focal-plane shutter 1 according to the present
embodiment employs the solenoid 80. For example, it is conceivable to
employ an actuator including a stator, a coil, and a rotor, instead of
the solenoid 80. However, if such an actuator is employed, the whole size
of the device is increased. The focal-plane shutter 1 according to the
present embodiment employs the solenoid 80, which can adsorb and hold the
first lever 40 when the solenoid 80 is not energized, thereby suppressing
an increase in the whole size of the device.

[0062] Further, if an actuator including a rotor is employed, rotary
torque of the rotor greatly fluctuates depending on a position of the
rotor. For this reason, the fluctuation of the rotary torque of the rotor
might increase a degree of the fluctuation of the moving speed of the
blades moved by the rotor, therefore, image quality might be influenced.
In the present embodiment, the first lever 40 is moved by the biasing
force of the spring S2, so that the moving speed is substantially
constant. Therefore, the moving speed of the leading blade 20a is
constant. Thus, in the focal-plane shutter 1 according to the present
embodiment, there is little influence on image quality.

[0063] Furthermore, if such an actuator is employed, the coil has to be
energized every time of rotating the rotor, since the rotor is rotated by
energizing the coil. Thus, power consumption might increase. In the
focal-plane shutter according to the present embodiment, the solenoid 80
can adsorb and hold the first lever 40 when not energized. The solenoid
80 is energized in only a case of causing the first lever 40 to recede
from the solenoid 80, whereby the first lever 40 recedes from the
solenoid 80 in accordance with the biasing force of the spring S1. This
suppresses power consumption.

[0064] Furthermore, if such an actuator is employed, the direction of
energization of the coil has to be switched between forward and reverse
directions, in order for the rotor to rotate forwardly or reversely. This
might make energization control of the coil complicated. The present
embodiment employs the solenoid 80, so the direction of energization of
the coil of the solenoid 80 has only to be a single direction. This
simplifies the energization control of the coil of the solenoid 80.

[0065] Also, if such an actuator is employed, the rotor is maintained at a
predetermined position by detent torque when the actuator is not
energized. Thus, for example, if the impact is applied to the device, the
rotor might be rotated and positionally displaced from a predetermined
position. In the present embodiment, the magnetic attractive force
exerted between the solenoid 80 and the first lever 40 can set greater
than the detent torque exerted in the rotor of such an actuator. This
prevents malfunction caused by the impact.

[0066] While the exemplary embodiments of the present invention have been
illustrated in detail, the present invention is not limited to the
above-mentioned embodiments, and other embodiments, variations and
modifications may be made without departing from the scope of the present
invention.

[0067] In the first mode, as illustrated in FIG. 6, the leading blade 20a
starts moving in the set state where the opening 11 is opened, so the
opening 11 is closed. After that, the leading blade 20a recedes from the
opening 11 to open the opening 11. Next, the trailing blade 20b closes
the opening 11. In this manner, a photograph is taken as exemplarily
described above. An electronic leading blade, instead of the leading
blade 20a, of the image sensor provided in the camera side, and the
trailing blade 20b as only the mechanical shutter, may be used for
shooting in an electronic leading blade mode. For example, in the set
state where the opening 11 is opened as illustrated in FIG. 6, the
leading blade 20a does not move, the image sensor sequentially stores
image signals at every pixel lines perpendicular to the moving direction
of the trailing blade 20b, and the exposure is performed in
synchronization with the mechanical trailing blade 20b which starts
closing the opening 11 after a desired exposure period elapses. In such a
manner, shooting may be performed. Thus, the exposure is controlled by
the mechanical operation of only the traveling of the trailing blade 20b
from the shutter fully opening state in the live view mode. It is
therefore possible to perform the shooting in a very silent manner. Also,
the electronic leading blade mode and the first mode are different from
each other only in whether or not the leading blade 20a closes the
opening 11 by the first lever 40, specifically, only in whether or not
the coil of the solenoid 80 is energized. As described above, the
direction of the energization of the coil of the solenoid 80 has only to
be a single direction, and the energization control is also simplified.
Thus, the first focal-plane shutter according to the present invention is
applicable to the electronic leading blade shooting mode of the camera
side with ease, in addition to the first mode and the second mode.

[0068] In the above embodiment, the spring S1 biases the leading blade 20a
to close the opening 11. One end S11 of the spring S1 engages with the
board 10 side, and the other end S12 engages with the first lever 40
side. However, the spring S1 is not limited to such a configuration. For
example, one end S11 of the spring S1 may engage with the second lever 50
side, the other end S12 of the spring S1 may engage with the first lever
40, and the first lever 40 may be biased to rotate toward the second
lever 50 in a state where the second lever 50 is set. For example, one
end S11 of the spring S1 may engage with the engagement portion 58, the
other end S12 of the spring S1 may engage with the engagement portion 48,
and the spring S1 may bias the engagement portion 48 and the engagement
portion 58 such that the engagement portion 48 and the engagement portion
58 abut with each other.

[0069] For example, an optical equipment including the focal-plane shutter
1 according to the present embodiment is a single-lens reflex camera, a
digital camera, or the like. Although the focal-plane shutter 1 according
to the present embodiment is applicable to the digital camera, the
focal-plane shutter 1 is also applicable to a silver film camera other
than the digital camera. That is, the focal-plane shutter 1 according to
the present embodiment is applicable to both of the digital camera and
the silver film camera, and the shutter can be commonly used for both
cameras.

[0070] Finally, several aspects of the present invention are summarized as
follows.

[0071] According to an aspect of the present invention, there is provided
a focal-plane shutter including: a board including an opening; a leading
blade and a trailing blade capable of opening and closing the opening; a
trailing blade lever capable of driving the trailing blade; a first lever
connected to the leading blade and capable of driving the leading blade;
a second lever arranged coaxially with the first lever, and having an
engagement portion abutting with the first lever to push the first lever
such that the leading blade opens the opening; a self-holding type
solenoid capable of holding the first lever such that the leading blade
opens the opening in a state where the self-holding type solenoid is not
energized; a leading blade electromagnet and a trailing blade
electromagnet respectively capable of holding the second lever and the
trailing blade lever in a state where the leading blade electromagnet and
the trailing blade electromagnet are energized; and a set lever setting
the second lever and the trailing blade lever such that the second lever
and the trailing blade lever respectively abut with the leading blade
electromagnet and the trailing blade electromagnet, wherein a first mode,
where the second lever and the trailing blade lever are set in a state
where the leading blade and the trailing blade open the opening, or a
second mode, where the second lever and the trailing blade lever are set
in a state where the leading blade closes the opening and the trailing
blade opens the opening, is selectively switched.

[0072] With such a configuration, the self-holding type solenoid is
employed instead of an actuator having a rotor, thereby suppressing an
increase in size of the focal-plane shutter.

[0073] According to another aspect of the present invention, there is
provided an optical equipment including the above focal-plane shutter.